Reduction of Fusarium head blight and deoxynivalenol in wheat with early fungicide applications of prothioconazole.

Abstract

Numerous studies have identified the benefit of fungicides applied at flowering (Zadoks Growth Stage (GS) 59-69) in the reduction of Fusarium head blight and the reduction of deoxynivalenol (DON) in harvested wheat grain. Two experiments were performed to identify the ability of prothioconazole (Proline) at three timings to reduce Fusarium head blight and resulting DON in harvested grain of wheat. Prothioconazole (150 g ha(-1)) was applied to plots of wheat at GS31, GS39, and GS65 in a full-factorial design. Plots were inoculated with Fusarium-infected oat grain at GS30 and mist-irrigated at GS65 to encourage head blight development. Plots were assessed for head blight symptoms at GS77 and harvested grain was analysed for yield, specific weight, thousand grain weight, and DON. Factorial analysis of variance (ANOVA) identified prothioconazole applications at each timing that resulted in significant reductions in Fusarium head blight and DON. The control achieved with combinations of spray timings was additive with no significant interactions. The control of Fusarium head blight at GS31, GS39, and GS65 was 50, 58 and 83%, respectively. The reduction in Fusarium head blight achieved by all three timings combined was 97% compared to the fully untreated control plots. The reduction of DON after application of prothioconazole at GS31, GS39, and GS65 was 27%, 49%, and 57%, respectively. The application of prothioconazole at all three timings achieved 83% reduction of DON compared with the fully untreated control plots. These experiments have determined, for the first time, significant additional head blight disease control and mycotoxin reduction with applications of a fungicide before flowering.